Recently, Organic Light Emitting Diode (OLED) display device, also referred to as electroluminescence display device, has been widely applied to a mobile communication terminal, a personal digital assistant (PDA), a pocket PC, etc., due to its outstanding features such as self-luminescence, no need of backlight, high contrast, small thickness, wide viewing angle, quick response, suitable for wide temperature range, simple structure, simple fabrication process, and so on. The OLED display devices are divided into a passive matrix type and an active matrix type. In the OLED display device of active matrix type, each OLED is controlled by a Thin Film Transistor (TFT) circuit, and high luminescence efficiency and good image display effect can be achieved.
A conventional OLED display device of active matrix type is shown in FIG. 1, and comprises a color filter substrate 10 and an array substrate 20. A fabrication process of the color filter substrate comprises: sequentially forming a color filter layer, a flattening layer 13, a first electrode 14, an organic electroluminescence (EL) layer 15 and a second electrode 16 on a first substrate 11. The color filter layer comprises a black matrix 121 and color filters 122 separated by the black matrix 121. A fabrication process of the array substrate comprises: forming a thin film transistor 22 on a second substrate 21, covering a protective layer 23 on the thin film transistor 22, and then forming a connection electrode 24 on the protective layer 23. The connection electrode 24 is electrically connected with a drain electrode the thin film transistor 22 through a via hole provided in the protective layer 23. Finally, a sealant 30 is coated on an edge of the color filter substrate 10 and/or array substrate 20, the color filter substrate 10 and the array substrate 20 are bonded with each other, and the second electrode 16 on the color filter substrate is in contact with the corresponding connection electrode 24 on the array substrate 20 so as to be electrically connected with each other.
In the above OLED display device shown in FIG. 1, the organic electroluminescence layer 15 is provided in a space enclosed by the color filter substrate 10, the array substrate 20 and the sealant 30; because the sealing effect of the sealant 30 is not enough, it is very easy for oxygen and moisture in the air to damage the organic electroluminescence layer 15, thus the service life and reliability of the OLED display device are degraded.